Osteoporosis is a major health problem in postmenopausal women. Our long-term goal is to develop a new complementary and alternative medicine (CAM) strategy featuring a dietary supplement and a mind-body exercise for alleviating bone loss in postmenopausal women with low bone mass. Objective: To test a CAM intervention including green tea polyphenol (GTP) and Tai Chi (TC) exercise for feasibility, and to quantitatively assess their individual and conjugate effects on postmenopausal women with osteopenia. Hypotheses: (1) 24 weeks of GTP supplement, TC exercise, and their combination will benefit bone remodeling as measured by bone biomarkers in postmenopausal women with osteopenia compared to those receiving placebo only, and (2) the changes in bone biomarkers associated with bone remodeling will be correlated with the changes in oxidative stress. The specific aims are: [unreadable] 1. To perform a 24-week randomized and placebo-controlled intervention trial in 140 postmenopausal women with osteopenia. Study participants will be assigned to 4 treatment arms: (1) placebo control group receiving medicinal starch pills daily, (2) GTP group receiving 1000 mg of GTP per day, (3) placebo+TC group receiving both placebo treatment and TC training (60-minute group exercise, 3 times per week), and (4) GTP+TC group receiving both GTP and TC treatments for 24 weeks. During the intervention, all participants will be provided with 1000 mg of elemental calcium and 400 IU of vitamin D daily. We will evaluate accrual rate, retention and compliance, adverse events, delivery of the intervention, appropriateness of inclusion/exclusion criteria, and optimization of the overall protocol design for the planned clinical trial. [unreadable] 2. To evaluate the effects of GTP, TC and their combined interventions on bone turnover and DNA damage oxidative stress biomarkers at baseline, 6, 12 and 24 wks. The bone turnover biomarkers will include bone formation biomarker (serum bone alkaline phosphatase) and bone resorption biomarker (urinary type I collagen cross-linked N-(NTX)). The oxidative DNA damage biomarker will be 8-hydroxy-2'- deoxyguanosine (8-OHdG) in urine. A model of repeated measurements with random effect error terms will be applied. Traditional procedures such as ANCOVA, chi-squared analysis, regression, and bivariate correlation will also be used for comparisons. [unreadable] Significance: The study will result in a new alternative rehabilitation treatment with proven anti-osteoporotic benefits for postmenopausal women with low bone mass. [unreadable] [unreadable] [unreadable]